Influences of Various Level of Water Depth on Rice Growth

The Journal of Geo-Environment ISSN 1682-1998 Vol. 4, 2004, PP. 23-30 (Printed in August, 2005)

Influences of Various Level of Water Depth on Rice Growth in Rice-Fish Culture Under Wetland Rice Ecosystems

M. Hazrat Ali*, M. Mahmuda Khatun**, Lun G. Mateo***

Abstract: The study was undertaken at the experimental farm of Philippine Rice Research Institute, Maligaya, Science City of Muñoz Nueva Ecija, Philippines to determine the effect of various level of water depth on rice growth under rice-fish culture in wetland rice ecosystems. The treatment with rice-fish at 16-20 cm water depth produced significantly the tallest plants whereas the treatments with rice-fish at 5-10 cm and 11-15 cm water depth and the control produced the shorter plants. The leaf area was increased progressively with plant age reaching its maximum value at 72 days after transplanting (DAT) and beyond 72 DAT leaf area declined because of leaf senescence. The values of LAI (Leaf area index) were maximum at 72 DAT for all the treatments except the treatment of rice+fish with 21-25 cm water depth and the control. The values of DM (Dry matter) were statistically similar among the treatments throughout the growing period but at harvest, consistently higher dry matter production was observed for the treatment of rice + fish with 11-15 cm water depth. This was lower in the treatment of rice+fish with 16-20 cm and the control.

Plant population at 17 DAT differed significantly among the treatments possibly due to uneven distribution of seedlings at planting and also damaged by Golden nails. Maximum tiller production was observed at 45 DAT for all the treatments and the highest number of productive tillers per hill as well as in unit area was obtained from the treatment with water depth of 16-20 cm followed by 21-25 cm. Rice plants were found lodged which was observed more importantly when they were grown beyond 15 cm of water depth

Introduction Rice is only the major food crop that can be grown in standing water. In wetland

* Rice Farming Systems Division, Bangladesh Rice Research Institute, Gazipur 1701.

(Corresponding author) ** Bio-technology Division, Bangladesh Agricultural Research Institute, Gazipur-1701. *** Department of Crop Science, Central Luzon State University, Science City of Muñoz,

Nueva Ecija, Philippines.

The Journal of Geo-Environment, 2004 24

rice, varying amounts of water are needed from the time of raising of seedlings to maturity. It is generally believed that peak water demand for rice is between maximum tillering and grain filling stage. Excess water depth at early rooting stage seriously hamper rooting and decrease tiller production and poor stand resulting lower yield. Literature's indicate that rice is the most sensitive to moisture stress from 20 days before heading to 10 days after heading.

Water is pre-requisite for raising fish and is also important for the growth and development of rice and perhaps that is the common characteristics for them.

Literature indicates that water requirements for integrated rice-fish culture are greater than for ,rice monoculture. According to Hora and Pillay (1962) fish culture in rice fields requires a minimum depth of water at about 3-5 cm during first two weeks after transplanting and gradually increasing to 15-20 cm. The depth of water requirement depends on the size and type of fish culture but it must be at least 10 cm for part of the culture period (Khoo and Tan, 1980). However, a water depth greater than 15 cm may delay maturity of rice (Moody, 1992). As the water requirement for rice-fish farming is greater and to some extent, higher water depth has negative implication on rice growth therefore, it is necessary to make compromise with water depth for obtaining maximum rice and fish yield. In this paper, the effect of various level of water on rice growth has been demonstrated.

Materials and Methods The study was conducted at the farm of Philippine Rice Research Institute, Maligaya, Muñoz Science City, Nueva Ecija, Philippines during dry season (DS) 2001 with 5 treatments, having 3 replications using Randomized Complete Block Design. The dimension of the experimental plots measured 11.6 m long and 10.6 m wide. To determine the influences of different levels of water depth, the trial was conducted with the following treatments viz. T1= Rice alone at 5-10 cm of water (Control), T2 = Rice-fish at 5-10 cm of water, T3 = Rice-fish at 11-15 cm of water, T4 = Rice-fish at 16-20 cm of water, and T5= Rice-fish at 21-25 cm water.

To provide adequate water as per treatments the dikes of each plot was made with base widths of 50 cm, top widths of 30-40 cm and heights of 40-50 cm as suggested by Sevilleja, et. al (1992).

The experimental field was prepared by conventional land preparation technique. A high yielding rice variety, PSB Rc 66 of 29 day old-seedlings were transplanted at a distance of 20 cm X 20 cm with 2-3 seedlings per hill. Chemical fertilizers at the rate of 120 N - 40 P2O5 - 40 K2O kg/ha were applied using conventional method of fertilization.

Various Level of Water Depth on Rice Growth 25

Shallow water depth (3-5 cm) was maintained during the first week of transplanting as a preventive measure against the herbivorous apple golden snail and quick seedlings establishment. Depth of water was increased as per treatments at the day of release of fingerlings. Water was monitored everyday following the imposed water depth. Golden snails were hand picked up to 7 days after transplanting to reduces nail's damage. Furthermore, replanting was also done at 7- days after transplanting.

Fingerlings of Nile tilapia (Orechromis niloticus) called GIFT (Genetically Improved Farmed Tilapia) were released with an initial body weight ranged of 10-15 g, average weight of individual 13.90g at 10,000 fingerling/ha at 11-days after rice transplanting. Supplementary feed was given two times in a day (1/2 at 7-8 a.m. and 1/2 at 4-5 p.m.) based on 10% of initial body weight. Fish was harvested at the same day of rice harvest after 79-day cultured period.

In order to determine the treatment effect of plant growth, data of biomass accumulation, leaf area and leaf area index (LAI) were assessed using destructive sampling and tillering pattern were monitored throughout the growing period. Plant height was determined at harvest.

Dry-matter production at growth stage was determined using destructive sampling of 4-hills which were separated into stem and leaf while, at flowering stage the samples were separated into stem, leaf and panicle. At harvest, mature plants were cut at ground level, threshed, cleaned, dried and weighed straw and grain separately. The harvested plants were dried in an aerated oven at 80°C (±5°C) for 48 hrs. The oven-dried samples were weighed separately to assess the value of dry matter production during the growing period. Root weight however, was not considered in estimating DM production because its omission has trivial consequence in total crop weight at harvest (Biscoe, et al 1975; Gregory, 1977) and more importantly it is very difficult to collect all root parts in field experiment.

In case of leaf area and LAI, the leaves of 4-hills sample were also separated into green and dead/brown leaves. Both green and dead/brown leaves were measured separately by using leaf area meter (model: Li-3l 00). LAI the ratio of total leaf area to total ground area covered by the sample was determined as follows:

Leaf area of sampled leaves

LAI = Land area covered by sampled leaves


Results and Discussion

Leaf area and leaf area index Leaf area (green and dead) was calculated from destructive sampling. The leaf area was increased progressively with plant age reaching its maximum value at 72 days after transplanting (DAT). Beyond 72 DAT leaf area declined because of leaf senescence (Fig.l). This result confirmed the findings of Yambao and Ingran (1988) who reported maximum leaf area at 70 DAT for IR 64. Results also indicated that the leaf started to decrease at 58 DAT onwards in all the treatments irrespective of water depth. Occurrence of leaf senescence followed a similar trend (Fig. 2).

The values of LAI were maximum at 72 DAT for all the treatments except the treatment of rice + fish with 21- 25 cm water depth and the control (Fig. 3). The results of LAI followed more or less a similar pattern to the values of leaf area. According to Tanaka (1973), when LAI is optimum, excess N nutrition enhances leaf growth. He also suggested that the maximum LAI for modern rice is 7. In this study, LAI, however, ranged from 1.41- 4.08 which means that N application was not adequate resulting in lower leaf growth.

Dry- matter production In cereal crops, dry-matter (DM) production is correlated with the amount of solar radiation absorbed by the foliage (Gallagher and Biscoe, 1978; Monteith and Elston, 1983), which is largely determined by the size of leaf and its distribution with time (Biscoe and Gallagher, 1978).

The values of DM were statistically similar among the treatments through out the growing period, which increased with age and was peak at 96 DAT (Fig. 4). At harvest, results indicated a promotion of consistently higher dry-matter production for the treatment of rice + fish with 11-15 cm water depth (4.14 g/plant) but lower in the treatment of rice + fish with 16-20 cm (3.56 g/plant), and the control.

Plant height Plant height was found to influenced significantly by water depth (Fig. 5.). Plant height generally depends on internodes expansion which might have caused increased in height with the increase of water depth resulted taller plants in the study. The height of rice plant is directly related to the depth of water and generally increases with increasing water depth (De Datta, 1981). According to Vergara et al. (1976), internodes elongation occurs in response to increase water depth as observed in deepwater and floating rices.


Tillering pattern Result indicated that at initial tiller counting, plant population significantly differed among the treatments (Table - 1). This was possibly due to uneven distribution of seedlings at planting and also damaged by Golden nails. Results further suggested that maximum tiller production was observed at 45 DAT for all the treatments. Highest number of productive tillers per hill as well as in unit area was obtained from the treatment with water depth of 16-20 cm followed by 21-25 cm. On the other hand, other treatments and the control produced similar number of panicles per unit area and per hill.

In cereal crops, plant density has a considerable influence on number of tiller production per plant that means a lower plant population compensates by higher tiller production and survival resulting higher grain yield. However, in the present study, there was no consistent relationship on tiller production and survival with plant population. Therefore, variations in the mean number of tiller per unit area and productive tiller per hill were observed most importantly in the treatment with fish at the water depth of 16-20 cm and 21-25 cm.

It was also observed that in some plots rice plants were found lodged which was observed more importantly when they were grown beyond 15 cm of water depth (Fig. 6)

Table 1. Tillering Pattern of PSB Rc 66 with Different Depths of Water

Under Rice-Fish Culture in Wetland Rice Ecosystems Treatments Tiller production (No.)

17 DAT m-2

31 DAT m-2

45 DAT m-2

59 DAT m-2

73 DAT m-2

Total m-2

Productive m-2

Tiller hill-1

Rice alone at 5-10 cm water depth (Control)

435b

629b

686

589

521

442

375

15

Rice+fish at 5-10 cm water depth

433b

632b

654

569

506

467

375

15

Rice+fis at 11-15 cm water depth

381a

554a

596

524

481

433

375

15


394a

552a

623

587

531

467

425

17


456b

636b

669

591

533

467

400

6

CV (%)

3.8

4.6

5.2

9.9

9.0

6.4

8.0

-




References

Biscoe, P. V., and J. N. Gallagher, 1978. A physiological analysis of cereal yield. 1. Production of dry-matter. Agric. Progress, 53, 34-50.

De Datta, S. K., 1981. Principles and Practices of Rice Production. Wiley and Sons. Ltd., Singapore.

Dela Cruz, C. R. 1980. Integrated agriculture-aquaculture farming systems in the Philippines, with two case studies on simultaneous and rotational rice-fish culture, P 209-224. In: R.S.V.Pullin and Z.H. Schehadeh (eds.) 1980. Integrated agriculture-aquaculture farming systems, ICLARM Conf. Proce. 4, 258p

Hora, S.L. and T. V. R. Pillay. 1962. Handbook on fish culture in the Indo-Pacific Region. Fish Bio. Tech. Pap. 14. Food and Agriculture Organization, Rome. 264p.

Khoo, H. and E. S .P. Tan. 1980. Review of rice-fish culture in Southeast Asia p. 1-14. In: R.S.V. Pullin, and Z. Shehadeh (eds.) 1980. Integrated agriculture-aquaculture farming systems, ICLARM Conf. Proc. 4, 258p.

Monteith, J. L. and D. J. E1soton, 1983. Performance and productivity of foliage in the field. In: J. E., De1a and F.L. Milthorpe (eds.) 1983. The growth and functioning of leaves. Cambridge University Press, Cambridge, pp.499-516.

Moody, K. 1992. Fish-crustacean-weed interaction. P 185-192. In: C.R. Dela Cruz, C. Lightfoot, B.A. Costa-Pierce, V.R. Carangal and M.P. Bimbao (eds.), 1992. Rice-fish research and development in Asia. International Center for Living Aquatic Resources Management (ICLARM). Makati, Manila, Philippines. ICLARM Conf. Proc. 24,457 p.

Sevilleja, R C. 1978. Alternative and modified management systems for rice-fish culture. Report of 17th Asian Rice Farming System Working Group Meeting, 5-11 Oct., 1986.

Tanaka, A. 1973. Influence of special ecological condition on growth, metabolism and potassium nutrition of tropical crops as exemplified by the case of rice. In: Mengel, K. and E. A. Kirk (eds.) 1978. Principles of plant nutrition. International Potash Institute, Switzerland.

Vergara, B. S., B. Jackson and S. K. De Datta, 1978. Deep water rice and its response to deep water stress. pp.301- 319 in IRRI. Climate and rice. Los Baños, Philippines.

Yambao, E. B. and K. T. Ingram. 1988. Drought stress index for rice. Philipp J. Crop Sci., 13 (2): 105-111.

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Influences of Various Level of Water Depth on Rice Growth